Currently the store pattern is not well followed.
Read here to see how to improve the following: https://vuejs.org/v2/guide/state-management.html, there: https://www.youtube.com/watch?v=7lpemgMhi0k and there: https://github.com/gothinkster/vue-realworld-example-app/tree/master/src/store

Currently anyone can use your token.
A good practice is to hide token and private information from repo.

Read more there: https://help.github.com/articles/removing-sensitive-data-from-a-repository/

A count could be anything. Try to be specific when naming, and use a score named variable

The socket.io emit new tweet. When tweet are receive by the socket.io client, the client could simply update the store with a mutation NEW_TWEET, then in your store, you would have an array of all the tweets you received.

This would allow to avoid the getLastTweet methods which looks a bit like a pile of 🍝!

The utils/index.js file contains a function with param and all magic operations which looks like mapping paras for something. But what thing ?

I like the fact that you use stylus.

Using standard-settings, you will enforce good standards:

• do not mix dev parameters and app settings
• do not override settings for user when pushing modifications
• hide private information

Read more here: https://github.com/soixantecircuits/standard-settings